Interferometric ring lasers and optical devices

Abstract

Two ring diode lasers are optically coupled together to produce tunable, stable output through a Y-junction output coupler which may also be a laser diode or can be an active waveguide. These devices demonstrate a sharp peak in light output with an excellent side-mode-rejection ratio. The rings can also be made of passive or active waveguide material. With additional rings the device is a tunable optical multiplexer/demultiplexer.

We claim: 
     
       1. An interferometric ring cavity optical waveguide apparatus comprising first and second ring cavities which are optically coupled for a portion of their lengths, means to provide input light into the first and second ring cavities, and means to transmit light out of the apparatus, wherein at least one of the ring cavities comprises lasing means. 
     
     
       2. An interferometric ring cavity optical waveguide apparatus comprising first and second ring cavities which are optically coupled for a portion of their lengths, means to provide input light into the first and second ring cavities, and means to transmit light out of the apparatus, wherein at least one of the ring cavities comprises a semiconductor active gain material. 
     
     
       3. The apparatus of claim 2 wherein each of the ring cavities with semiconductor active gain material is connected by separate electrical contact means with means to drive that gain material. 
     
     
       4. The apparatus of claim 3 wherein at least one of the ring cavities is provided with means to input light. 
     
     
       5. The apparatus of claim 3 wherein the output means comprises a semiconductor active gain material that is electrically connected to means to vary the gain or loss of the material to modulate the amplitude of the output light. 
     
     
       6. An interferometric ring cavity waveguide apparatus comprising first and second ring cavities, at least one of which comprises laser diode means, which are optically coupled for a portion of their lengths and formed on a substrate and light output means coupled to one of the ring cavities. 
     
     
       7. The apparatus of claim 6 wherein the light output means comprises an active gain semiconductor material. 
     
     
       8. The apparatus of claim 6 wherein the two cavities and the output means each have separate electrode means. 
     
     
       9. The apparatus of claim 6 wherein the first and second cavities and the output means comprise diode laser means. 
     
     
       10. The apparatus of claim 9 wherein the diode laser means in the first and second cavities and in the output means all share a common electrode of one polarity and each of the three has a separate electrode for the other polarity. 
     
     
       11. The apparatus of claim 9 wherein the output face of the output means is not perpendicular to the axis of the output means. 
     
     
       12. The apparatus of claim 9 wherein the apparatus further comprises photodetector means optically connected to the output means. 
     
     
       13. The apparatus of claim 12 wherein the apparatus further comprises feedback means responsive to the electrical output of the photodetector means, which includes means to control the current injected into the diode laser means. 
     
     
       14. The apparatus of claim 13 wherein the feedback means includes means to maintain the optical power from the output means at its peak level within the normal operating range of the apparatus. 
     
     
       15. The apparatus of claim 13 wherein the apparatus further includes a logic current input line connected to one of the ring cavities and to the feedback means such that the feedback means includes: first means to hold the output power of the apparatus at a first power level which is sufficiently lower than the peak power level to establish a different logic state than that represented by the peak power level by controlling the injected current level at a first current level which is less than that necessary to produce the peak power in the absence of any added current from the logic current input line and   second means to hold the injected current level at a second level sufficient to produce peak power when the sum of the first current level and the logic current level equals this second level.   
     
     
       16. The apparatus of claim 15 wherein the apparatus further includes third means to hold the output power at a third power level equivalent to the first power level when the sum of the injected current at the first current level and the logic current is sufficient to produce this third level. 
     
     
       17. The apparatus of claim 9 wherein the apparatus further comprises a third ring cavity comprising a laser diode material optically coupled to the first cavity, an optical input line to the first cavity, the light output means being connected to the second cavity, and an additional light output means being connected to the third ring cavity, thereby forming a channel-drop filter means. 
     
     
       18. The apparatus of claim 10 wherein at least one of the separate electrodes is connected to means to modulate the signal to that electrode such that the light output is modulated with respect to amplitude, wavelength or phase.